This invention was made with no United States government support.
The present invention relates to a method of enhancing plant or seed health in order to protect plants or seeds from stress-related injuries. Additionally, the present invention relates to a method of enhancing or accelerating the recovery of plants suffering from stress-related injuries. Finally, the present invention relates to a method of enhancing the germination of seeds and seedling vigour.
The yield and quality of desired plant products is determined by the health of the plant. A healthy plant is one which is able to withstand biotic (pathogens, insects, etc.) stresses as well as abiotic (cold, heat, drought, etc.) stresses. Conversely, a weak plant is one which succumbs to pathogen and/or environmental stresses. During imbibation, dry seed experiences stresses due to sudden rehydration. These stresses can impact both the extent and speed of seed germination. A healthy seed is one which is able to germinate faster and thus get a head start. Such a head start improves the seed""s chances of increasing its yield, especially in areas with shorter growing seasons. The commercial value of seed is determined in part on percentage (%) germination, rate of germination and the robustness of the seedling produced. There is a great interest in improving these properties of commercial seeds.
Mature seeds of most crop plants contain very little moisture. These seeds can be stored for a long time in dormant stage. The living portion of the seed, the embryo, remains inactive in dehydrated state as long as the seed is remains dry. When these seeds are sown in the soil a rapid rehydration occurs. During this process, the embryo cells rehydrate and expand. Cell membranes are assembled into an organized structure that preserves the integrity of the cells. However, since rehydration is generally quick, the cell membrane is not fully assembled in the initial phase of rehydration. This results in some leakage of cellular contents. During rehydration, since membranes are xe2x80x98leakyxe2x80x99. Important molecules, including proteins, carbohydrates and inorganic molecules, are known to leak in the initial phase of rehydration. This leakage of important cellular constituents is known to cause injury or stress to the embryo. Leakage of cellular constituents has been associated with the failure of seeds of many crops plants to germinate and/or produce healthy seedlings. Many seeds fail to germinate if the leakage of cellular solute is significant. xe2x80x9cSeed primingxe2x80x9d is intended to impart xe2x80x9chealthxe2x80x9d to the embryo cells so that leakage (thereby injury) to the embryo can be minimized.
The injury of crops as a result of abiotic and biotic stresses has been a major problem in the agricultural production areas of the U.S. Specifically, over 60% of the crop loss for last 50 years has been due to abiotic stresses (see USDA Agricultural Statistics, 1998). Abiotic stresses include chilling, freezing, drought, heat, and other environmental factors. In 1996, the loss of crop yield due to abiotic stresses was recorded to be more than a billion dollars in the U.S. (see USDA Agricultural Statistics, 1998). Thus, there is a tremendous interest in the plant industry to find a technology that can be used to prevent or mitigate stress injury and to accelerate recovery following a stress injury.
Lysophospholipids are derived from membrane phospholipids by the removal of a fatty acid by the action of an enzyme phospholipase A2. Lysophospholipids are naturally present in plant and animal tissues, and can be found in high concentrations in egg yolk, brain tissue, and soybeans. Lysophospholipids are available commercially from Avanti Polar Lipids, Inc. (Alabaster, Alabama) and from Sigma Chemical Co. (St Louis, Mo.). Lysophospholipids, such as lysophosphatidylethanolamine (hereinafter referred to as xe2x80x9cLPExe2x80x9d) and lysophosphatidylinositol (hereinafter xe2x80x9cLPIxe2x80x9d), have been exploited for accelerating fruit ripening, enhancing fruit stability during storage, and increasing the shelf life by retarding senescence of plant tissues such as fruits, vegetables, and cut-flowers. Farag, K. M. et al., Physiol. Plant, 87:515-524 (1993), Farag, K. M. et al., HortTech., 3:62-65 (1993), Kaur, N., et al., HortScience, 32:888-890 (1997), Ryu, S. B., et al., Proc. Natl. Acad. Sci. USA, 94:12717-12721 (1997). Methods for using LPE to enhance fruit ripening and storage stability are disclosed in U.S. Pat. Nos. 5,126,155 and 5,100,341. Methods for using LPE with 18:1 fatty acid and LPI to retard senescence and to enhance fruit ripening is described in WO 99/23889.
The present invention relates to a method of enhancing plant or seed health in order to prevent injuries to a plant or seed upon exposure to a stress. The method involves applying to a plant or seed before exposure to a stress, an effective amount of a composition containing at least one lysophospholipid(s) and optionally, at least one activating agent. The preferred lysophospholipids contained in the composition are LPE and LPI.
Additionally, the present invention further relates to a method of enhancing the recovery of a plant injured as a result of stress. The method involves applying to a plant after exposure to stress, an effective amount of a composition containing at least one lysophospholipid(s) and optionally, at least one activating agent. The preferred lysophospholipids contained in the composition are LPE and LPI.
Finally, the present invention relates to a method of enhancing the germination of seeds. The method involves treating seeds with a composition containing at least one lysophospholipid(s) and optionally, at least one activating agent. The preferred lysophospholipids contained in the composition are LPE and LPI.